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ring-buffer: raw spinlock fix

PATCH In review Steven Rostedt 2 participants 3 messages Nov 6, 2008

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Steven Rostedt

author maintainer
#0 lore raw

cover ring-buffer: raw spinlock fix

Ingo,

The following patches are in:

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git

branch: tip/devel

Steven Rostedt (1):
ring-buffer: convert to raw spinlocks

author maintainer
#1 lore raw

PATCH 1/1 ring-buffer: convert to raw spinlocks

Impact: no lockdep debugging of ring buffer

The problem with running lockdep on the ring buffer is that the ring buffer is the core infrastructure of ftrace. What happens is that the tracer will start tracing the lockdep code while lockdep is testing the ring buffers locks. This can cause lockdep to fail due to testing cases that have not fully finished their locking transition.

This patch converts the spin locks used by the ring buffer back into raw spin locks which lockdep does not check.

Signed-off-by Steven Rostedt <[email protected]>
---
 kernel/trace/ring_buffer.c |   31 ++++++++++++++++++++-----------
 1 files changed, 20 insertions(+), 11 deletions(-)
kernel/trace/ring_buffer.c +20 -11
index a84a187..6781e9a 100644
@@ -154,7 +154,7 @@ static inline int test_time_stamp(u64 delta)
 struct ring_buffer_per_cpu {
 	int				cpu;
 	struct ring_buffer		*buffer;
-	spinlock_t			lock;
+	raw_spinlock_t			lock;
 	struct lock_class_key		lock_key;
 	struct list_head		pages;
 	struct buffer_page		*head_page;	/* read from head */

@@ -291,7 +291,7 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
 
 	cpu_buffer->cpu = cpu;
 	cpu_buffer->buffer = buffer;
-	spin_lock_init(&cpu_buffer->lock);
+	cpu_buffer->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
 	INIT_LIST_HEAD(&cpu_buffer->pages);
 
 	page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),

@@ -854,7 +854,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 	if (write > BUF_PAGE_SIZE) {
 		struct buffer_page *next_page = tail_page;
 
-		spin_lock_irqsave(&cpu_buffer->lock, flags);
+		local_irq_save(flags);
+		__raw_spin_lock(&cpu_buffer->lock);
 
 		rb_inc_page(cpu_buffer, &next_page);
 

@@ -930,7 +931,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 			rb_set_commit_to_write(cpu_buffer);
 		}
 
-		spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+		__raw_spin_unlock(&cpu_buffer->lock);
+		local_irq_restore(flags);
 
 		/* fail and let the caller try again */
 		return ERR_PTR(-EAGAIN);

@@ -953,7 +955,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 	return event;
 
  out_unlock:
-	spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+	__raw_spin_unlock(&cpu_buffer->lock);
+	local_irq_restore(flags);
 	return NULL;
 }
 

@@ -1540,7 +1543,8 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
 	unsigned long flags;
 	int nr_loops = 0;
 
-	spin_lock_irqsave(&cpu_buffer->lock, flags);
+	local_irq_save(flags);
+	__raw_spin_lock(&cpu_buffer->lock);
 
  again:
 	/*

@@ -1602,7 +1606,8 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer)
 	goto again;
 
  out:
-	spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+	__raw_spin_unlock(&cpu_buffer->lock);
+	local_irq_restore(flags);
 
 	return reader;
 }

@@ -1871,9 +1876,11 @@ ring_buffer_read_start(struct ring_buffer *buffer, int cpu)
 	atomic_inc(&cpu_buffer->record_disabled);
 	synchronize_sched();
 
-	spin_lock_irqsave(&cpu_buffer->lock, flags);
+	local_irq_save(flags);
+	__raw_spin_lock(&cpu_buffer->lock);
 	ring_buffer_iter_reset(iter);
-	spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+	__raw_spin_unlock(&cpu_buffer->lock);
+	local_irq_restore(flags);
 
 	return iter;
 }

@@ -1959,11 +1966,13 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
 	if (!cpu_isset(cpu, buffer->cpumask))
 		return;
 
-	spin_lock_irqsave(&cpu_buffer->lock, flags);
+	local_irq_save(flags);
+	__raw_spin_lock(&cpu_buffer->lock);
 
 	rb_reset_cpu(cpu_buffer);
 
-	spin_unlock_irqrestore(&cpu_buffer->lock, flags);
+	__raw_spin_unlock(&cpu_buffer->lock);
+	local_irq_restore(flags);
 }
 
 /**
Signature · 3 lines
1.5.6.5

--
#2 lore raw
In reply to Steven Rostedt
Quoted 10 lines · Steven Rostedt

Ingo,

The following patches are in:

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git

branch: tip/devel

Steven Rostedt (1):
ring-buffer: convert to raw spinlocks

i've pulled these 3 commits from you:

77b93a0: ring-buffer: convert to raw spinlocks 615a23a: ftrace: restructure tracing start/stop infrastructure 93411d5: ftrace: soft tracing stop and start
da0f875: ftrace: add quick function trace stop

I topicized them into tip/tracing/ftrace, so the sha1's are different.

thanks Steve!

Ingo